Scanners are devices which are used to control the movement of a beam of light, such as from a laser. The scanners are employed to aim optical elements such as mirrors, lenses and the like in order to reflect, collect and focus light. Scanners have found extensive application in the bar code industry. Bar codes consist of alternating light and dark bars which are used to present price or other information. One conventional method for reading them is to scan a focused beam of light in a line across the entire code. As light is absorbed and scattered by the bars, the resulting light modulation may be detected by a photodiode, for example, and processed by an electronic cash register or computer terminal.
In hand held bar code reading equipment compactness and simplicity of the scan mechanism are essential so the equipment can be portable. Single straight line scans are the simplest to generate and thus are often used in such equipment.
Orientation of the scanning beam with respect to the bar code is required however and this can slow down the reading process in either portable or fixed mount scanners. Various systems have therefore been devised to automatically scan a beam in multiple directions to overcome the need for tedious orientation.
U.S. Pat. No. 4,387,297 disclosed a portable scanning system in which a pair of motors and multiple drives are used to generate an omnidirectional pattern. Refinements of this device have not yet obviated the inherent clumsiness and size of the device due to the multiple drives and other equipment. Another beam scanning type device, shown in U.S. Pat. No. 4,639,070, uses an involved gear system for rotating various elements of the device. It also is quite complicated to manufacture.
U.S. Pat. No. 4,041,322 describes a device in which there is an angular displacement of a mirror in a single plane and at a constant speed. Several mirrors are used to provide the scanning signal at various angles.
U.S. Pat. No. 4,494,024, describes a spring activated motor, but it is a "one shot" spring driven motor in which heat is used to release torque by severing a chord. U.S. Pat. No. 3,631,274 describes a power supply in which a spring induces a voltage pulse in the coil.
U.S. Pat. No. 4,388,651 describes the faults of the prior art, stating that it is characterized generally by considerable complexity or by limited performance. This patent proposes to solve the problem using a single, small diameter rotating polygon mirror which is described as having increased scan efficiency by reflecting a beam from the polygon mirror facets two separate times. Examples of other systems are shown in U.S. Pat. No. 4,794,237, which employs a plurality of mirrors and a rotating disc, and in U.S. Pat. No. 4,795,224 which requires several motors and a relatively complicated prism ring which refracts light.
None of the prior art has yet been able to generate an appropriate optical pattern of lines to read bar codes at any orientation. Moreover, no prior art device has been found to produce omnidirectional scan patterns with a single optical element. Ideally, such a device would be small and very rapid, and could be held in one hand if constructed as a raster or omnidirectional device. It is desirable that the device be programmable to present one or more than one pattern of light with the fewest possible parts.
It is an object of this invention to provide a device for providing movement on an axis, such that a mirror can be attached to that axis, in order to impart combinations of rotational and x or y movement. Preferably the device imparts both movements, in order to generate a two dimensional scanning pattern produced by light reflected off on the mirror.
It is a particular object of the present invention to produce laser scan patterns which greatly reduce or eliminate the need for special orientation of either the bar code or the scanner in bar code reading equipment.
Yet another object is to provide a scanner which is programmable and yet which is small and compact, and which operates at low power.
In it broadest form, the object of this invention is to provide a means for aiming or positioning an optical element in synchronization with electronic signals, which may be produced by oscillators, computers, music, voice, and the like, for information gathering or demonstration or entertainment purposes.
Other objects will appear hereinafter.